According to Drug.com's Pill Identifier, a round white pill imprinted with 'M' and 'A21' is Alprazolam Extended-Release, 0.5mg.
oxycodone
Tapentadol (Nucynta) 100mg
I think its morphine but the m with the box might just be for the manufacture
Viagra
It is a Oxycodone 30mg
A blue, round pill, imprinted with "031, R" is Xanax 1mg.A blue, round, pill, imprinted with "MYLAN A1" is Xanax 1mg.A blue, round pill, imprinted with "XANAX 1.0" is Xanax 1mg.A blue, oval pill, imprinted with "G3721" is Xanax 1mg .A blue, round pill, imprinted with "b 493, 2" is Xanax XR 2mg .A blue, round pill, imprinted with "2, X" is Xanax 2mg.XR = (Extended Release)
Lovastatin 20 mg
If it were a drug (small round white pill, M over 15), it might be Lomotil, an antidiarrheal.
A blue oval shaped pill with a SL 20 and M on the pill are sildenafil 20 mg.
Generally a round blue pill or a blue capsule for XRs
APAP Butalbital Caffeine